扬子陆块西南缘东川大窑湾古元古代晚期辉长岩年代学、地球化学特征及地质意义OA

The southwestern margin of the Yangtze Block is extensively intruded by Paleoproterozoic mag-matic rocks;however,significant controversy persists regarding their tectonic setting and dynamic mechanisms.Gabbro,as the direct crystallization product of mafic magma,provides zircon U-Pb isotopic chronology data that can precisely constrain the timing of tectonothermal events.Furthermore,its major and trace element composi-tions effectively record the material exchange and energy transfer processes between the lithosphere and astheno-sphere,offering critical geochemical constraints for discriminating tectonic environments.This paper presents a systematic isotopic chronological and geochemical study of the Dayaowan gabbro in the Dongchuan area.The re-sults show that the zircon U-Pb age of the gabbro is(1 674±16)Ma,indicating its emplacement during the Late Paleoproterozoic.The rock belongs to the subalkaline series,exhibiting flat or slightly right-inclined patterns in chondrite-normalized rare earth element(REE)diagrams.In primitive mantle-normalized trace element spider dia-grams,it displays enrichment in large-ion lithophile elements(LILEs)including Ba,Sr,and La,along with rela-tive depletion in high-field-strength elements(HFSEs)such as Nb,Ta,and Hf.These geochemical characteristics share affinities with both within-plate basalts(WPB)and enriched mid-ocean ridge basalts(E-MORB).Compre-hensive analysis suggests that this magmatic activity likely formed in an intracontinental rift setting associated with mantle plume activity,representing a tectonic-magmatic thermal event response on the southwestern margin of the Yangtze Block during the breakup of the global Columbia Supercontinent.